Editing Chesapeake and Ohio Canal (section)

===Lift locks and guard locks===
{{Main|Locks on the Chesapeake and Ohio Canal}}

To build the canal, the C&O Canal Company used a total of [[Locks on the C&O Canal|74 lift locks]] that raised the canal from sea level at Georgetown to {{convert|610|ft|m}} at Cumberland.<ref name="hahn7">[[#hahn-pathway|Hahn, Pathway]], 7.</ref> Locks 8–27 and their accompanying lock houses were made from Seneca red sandstone, quarried from the [[Seneca Quarry]], as was Aqueduct No. 1, better known as [[Seneca Aqueduct]]. This unique structure is the only aqueduct made from Seneca red sandstone and is doubly unique for being the only aqueduct on the C&O that is also a lock (Lock 24, [[Riley's Lock]]).<ref>{{cite book|last=Peck|first=Garrett|title=The Potomac River: A History and Guide|year=2012|publisher=The History Press|location=Charleston, SC|isbn=978-1-60949-600-5|pages=62–63}}</ref>

Seven guard locks, often called '''inlet locks''' (numbered 1 through 8) were built to allow water and sometimes boats (particularly at Big Slackwater and Little Slackwater) to enter. Dam #7 and Guard Lock #7 were proposed (near mile 164 at the South Branch of the Potomac) but never built.<ref>[[#Unrau|Unrau]] p. 208 footnote, 470</ref> In 1856, there was a steam pump put at that site. Later, in 1872, a new steam pump was put near mile 174.

Three additional river locks were built, to allow boats to enter the canal at the river, as demanded by the Virginia legislature for buying canal stock. They were at Goose Creek (below Edwards Ferry, Lock 25), near the Shenendoah River just below Lock 33, and at Shepherdstown.

The Goose Creek locks were to allow boats from the '''Goose Creek and Little River Navigation Company''' to enter. Only one Goose Creek boat was documented to enter the C&O canal, and there is no documentation of a C&O boat entering Goose Creek. The lock was eventually converted into a waste weir.<ref>[[#hahn-towpath|Hahn, Towpath Guide]] p. 62-63</ref>

The Shenandoah river (about {{convert|422|ft}} below Lock 33) lock let boats cross to Harpers Ferry with the mules walking on the railroad bridge, up the Shenandoah river, to the old Potomac Canal Bypass on the Shenandoah river by Virginius island. The railroad refused to let mules walk on the bridge, and from lack of business, the lock was abandoned. Stones from that lock were used for other purposes.<ref>[[#hahn-towpath|Hahn, Towpath Guide]] p. 99-100</ref>

After the 1889 flood destroyed the nearby dam in Shepherdstown, the raison d'être for the Shepherdstown lock was gone, and so it was filled in.<ref>[[#Unrau|Unrau]] p. 167, 238</ref>

At night, lock tenders were required to remove the cranks and handles from all paddle valves to prevent unauthorized use.<ref name="Unrau P. 336">[[#Unrau|Unrau]] p. 336</ref>

====Composite locks====
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Despite Mercer not wanting any composite locks, due to measures to economize on the last {{convert|50|mi}} of construction, and the scarcity of good building stone, Locks 58–71 were constructed as composite locks, whereby the lock masonry is built of rubble and inferior undressed stone. Since that makes a rough surface which damages the boats, the locks were originally lined with wood to protect the boats. This wood sheathing had to be replaced.<ref>[[#Kytle|Kytle]] p. 71-72.</ref> In time, some of the composite locks were lined with concrete, since the wood kept rotting.